|“Only a Fusion Dragon can punch the depths of the Boiling Sea, and only the Dragon Blade can create one.”|
|— Ray, Out of the Fire and Into the Boiling Sea|
The Dragon Blade (also referred to as the Dragon Dagger) is a double-bladed dagger that is used to create the Fusion Dragon.
In the set, it consists of two blades, blue and red, joined by a golden connector.
In the episodes, it is made of two dragon-shaped blades, with a golden connector joining them. The connector has two lines, blue and red respectively, indicating which side is for which element.
- Dragon Summoning: By having an Elemental Master of Water and Fire channel their elements towards the blade, the Fusion Dragon can be summoned.
- Fighting: The blade can be used for basic fighting.
Kai discovers the blade in the secret room after hitting a gong in the shop, revealing a secret trapdoor. Wondering what else his father has been working on, he discovers an old Vermillion helmet and realizes that his father is still alive. Before he left, he takes the Dragon Blade.
Kai uses the blade to confront and fight his father. After Krux and Acronix arrives and reveals that Wu will die if they do not recover the Reversal Time Blade, Krux takes the blade from Kai.
Ray and Maya explain the concept of summoning the Fusion Dragon to Kai and Nya with the Dragon Blade. Together, they used the dragon to get close to the location of where Ray and Maya stored the Reversal Time Blade within the Boiling Sea. Arriving at the final trial, Nya and Kai use the blade to open the door to the Reversal Time Blade. After retrieving the Reversal Time Blade, the entire area becomes volatile, forcing the two to summon the Fusion Dragon to escape.
After being paused and left behind at the Boiling Sea, the pause effect wore off, causing Kai, Nya, Ray, Maya and Wu to begin to fall. Nya throws the blade into the air and together they re-create the Fusion Dragon and pick up Wu, Ray and Maya before they fell into the Boiling Sea.
Kai and Nya used the Dragon Blade to create the Fusion Dragon in order to combat the Iron Doom.